Pat lamb shoulder chunks dry and season well with salt and pepper. Heat vegetable oil in a Dutch oven or medium pot over medium-high heat. Once pan is hot add lamb and sear on all sides until golden-brown. Transfer to a plate and set aside.
Add onion, carrots, and parsnips to pan drippings and saute over medium-high heat 3-5 minutes until onion is translucent. Add garlic and cook 1-2 minutes until fragrant.
Pour Guinness into pot and use a wooden spoon to scrape up any browned bits. Bring to a simmer over medium-high heat, then reduce heat to medium-low and allow to simmer 3-5 minutes until Guinness is reduced a bit.
Add lamb, baby potatoes, beef broth, cornstarch-water mixture, thyme sprigs, and bay leaf to pot and stir until evenly combined. Bring to a simmer over medium-high heat, then reduce heat to medium-low, cover pot, and allow to simmer 45-60 minutes, stirring occasionally until lamb and vegetables are fork-tender.
Remove thyme sprigs and bay leaf and discard. Season stew with salt and pepper to taste and serve warm with bread for dipping. Enjoy!
Notes
Storing InstructionsStore stew in refrigerator up to 6 days. Stew may also be frozen up to 2 months.